250 HISTOLOGY 



out, but they never pass through the muscularis mucosae into the submu- 

 cosa. In the adult the upper group may be seen with the naked eye as an 

 "erosion" of the mucous membrane. The glands produce a form of 

 mucus which stains less readily with the mucus-stains than that of the 

 deep glands. No special function has been assigned to this secretion. 

 Glands of the lower group are shown in Fig. 243. They are freely branch- 

 ing mucous glands, the ducts of which open at the tops of connective tissue 

 papillae. They very frequently show cystic enlargements. 



d e f g 



FIG. 243. LONGITUDINAL SECTION THROUGH THE JUNCTION OF THE HUMAN (ESOPHAGUS 



AND STOMACH. X 60. 



a, Duct of a superficial cesophageal gland; b, oesophageal epithelium; c, gastric epithelium; d, tubule of 

 the gland a; e, lymphoid nodule; f, lymphatic vessel; g, lamina muscularis mucosae. 



The tunica propria in the oesophagus has fewer cells in its meshes than 

 that of the lower parts of the digestive tube. In places it includes solitary 

 lymph nodules. The muscularis mucosae is very wide in the oesophagus. 

 It is a layer of longitudinal smooth muscle fibers, which is thrown into longi- 

 tudinal folds when the oesophagus is contracted. It begins anteriorly at 

 the level of the cricoid cartilage, arising as scattered bundles inside the 

 elastic layer of the pharynx. As the muscles increase to form a distinct 

 layer, the elastic lamina terminates. The submucosa is a loose connective 

 tissue layer, containing many vessels and nerves, groups of fat cells, and 

 the bodies of the deep mucous glands. The muscularis consists of an inner 

 circular and an outer longitudinal layer, as elsewhere in the digestive tube, 

 but in the upper part of the oesophagus the layers are composed of striated 



